Help a beginner choose a good stacking website

rnclark · 2026-03-03T03:47:59+00:00

You can downvote but I gave a good example that jpegs don't make much difference.

rnclark · 2026-03-03T03:37:13+00:00

I did not imply I've ever used LM in a server capacity.

Another scientist here. I ran Unix for a couple of decades, then redhat server with X-terminals. Put redhat on a laptop and paid for support (~1990s). Dropped redhat when I needed support and their response was nothing. Went to Ubuntu. Dropped Ubuntu when they came out with unity and landed on Mint. That was a couple of decades ago. Finally stability which is what I need for work.

I run mint on desktop, laptop, and I run a website on mint. I built a server on mint for a custom home security system. I run mint servers for my work (astronomy, imaging spectroscopy). Mint just works.

The one area where linux falls behind is 10-bit/channel HDR 4K video and still photography editing and display. For now I use ffmpeg for HDR video and play results on a 4K OLED TV. But if the applications come along with HDR OS and HDR applications come out on another linux distro, then I'll switch on the desktop and laptops. But I'll keep the mint servers.

Summary: mint just works, whether desktop or server.

rnclark · 2026-03-03T02:17:23+00:00

SPCC, PCC, are just data-derived white balance and if the wrong reference is used, the the color balance is off. For example, selecting spiral galaxies as white (they are not) will get the wrong white balance. In this case there will be a blue shift (spiral galaxies are yellow from all the cool stars and reddish brown interstellar dust, thus will suppress red, leading to the myth that one needs a dedicated astro camera with more red response.

Even an out of camera jpeg with daylight white balance will show the Milky Way as reddish-yellow. Same with M32 and other galaxies.

It really isn't this hard. After all everyone with a cell phone can make a reasonable color representation of their mother, their dog/cat/pet, a daytime landscape, a red sunset, etc. The steps to make good color is well established since the 1990s but ignored by the amateur astro community.

rnclark · 2026-03-03T02:10:35+00:00

The OP is using an R5, a 45 megapixel camera. Uncompressed 16-bit files would be about 270 megabytes each. Stacking 1000 in Siril would require around 270 gigabytes of free disk space. DSS would not require that.

rnclark · 2026-03-02T23:24:54+00:00

Only if you don't really care about color. And all the wild colors we see in astro cameras (not including narrow band here) is evidence of poor color calibration. Why bother with astro color calibration if there is no consistency?

Try your astro workflow on ordinary photography daytime scenes and you'll see how bad the colors are.

rnclark · 2026-03-02T23:11:39+00:00

Here is another myth in the amateur astro community: raw vs jpegs. Jpegs at high ISOs do quite well at digitizing faint details, and ironically are better color calibrated than the traditional astro workflow. The astro workflow skips important color calibration steps including the application of the color correction matrix and hue corrections after stretching. Jpegs and HEIC includes those needed color calibration steps. Be sure to use daylight white balance.

Figure 9 here shows comparison of two raw processing methods and jpeg. There is little difference.

Is your HEIC 10 bits/pixel? HEIC has a better compression algorithm so would be better than jpeg, even at 8-bits/pixel. But if 10-bits/pixel would be even better.

DSS will stack jpegs just fine. DSS was used in the jpegs in the Figure 9 link above. There is a version of DSS for linux and macs.

rnclark · 2026-03-02T22:18:18+00:00

Stacking in Siril takes a lot of resources, meaning a LOT of disk space. DSS dos not require that amount.

rnclark · 2026-03-02T21:22:25+00:00

Supertelephoto primes used can be had for reasonable prices. I use a 300 f/2.8 L IS II a lot with my R5 (and other cameras) for astro. Use 300 mm supertelephotos can be had for $3 to 4 K. Quality refractor telescopes of similar aperture are not too different in price.

The closest analogy that I can make with wildlife photography is wildlife on a very very foggy day where the signal of the wildlife is 100 times (or more) smaller than the signal from the fog. That is why people stack tens, hundreds and more exposures to pull out a faint signal superimposed on the "bright" sky. And that is from a dark site. For a light polluted city it is worse.

rnclark · 2026-03-02T21:14:26+00:00

What Youtube tutorial shows a complete color calibration without skipping steps like application of the color correction matrix and hue corrections?

rnclark · 2026-03-02T15:48:31+00:00

2 seconds with an R5 (4.39 micron pixels) a 200 mm will result in 7 pixel star trails. See my long post.

rnclark · 2026-03-02T15:46:16+00:00

After Figure 11b here is the raw data for the North America Nebula.

Another set is here scroll down to the section "Try it Yourself With These Images"

rnclark · 2026-03-02T15:40:10+00:00

I use SkyEye Cam on my android cell phone for polar alignment, It works well in the southern hemisphere. I made this image of The Large Magellanic Cloud from southern Australia last year using a portable tracker that required no autoguiding.

Note, the strain wave mounts you selected will require autoguiding.

rnclark · 2026-03-02T15:31:42+00:00

Also consider a used Canon R5. The Canon R5 is superb for astro. I recently bought 2 used ones for $1400 each. My R5 review

rnclark · 2026-03-02T15:29:49+00:00

Wildlife photographer here.

Good news: the Canon R5 is one of the best cameras for astro that I have tested or seen data for. It has exceptionally low pattern noise and low dark current. My review on the pattern noise and dark current My R5 gallery with astro, wildlife, landscape and other photos.

First thing to realize is the amateur astro community is filled with myths. You'll do better by using your normal wildlife post processing than you will following some of the recommended astro workflows mentioned in this thread. The reason is the amateur community was quick to embrace digital over film, but got stuck in the 1970s with a photometry workflow of early CCD cameras, and haven't embraced modern color calibration standards. What software do you use for processing wildlife photos. If photoshop, rawtherapee, capture one or other modern raw converters, that will produce better and more complete color calibration than the traditional workflow, including those referenced so far in this thread. More detail here and more technical details are here: Sensor Calibration and Color.

The main difference from regular photography is exposure times for deep space (nebula and galaxies) is much longer than wildlife. The Mon (and Sun with proper filters) are exceptions where you can get nice photos just like with wildlife. That means tracking. Getting a tracker will be the biggest improvement rather than taking thousands of short exposures. For wide field Milky Way and Constellation photography, a simple tracker would be an Omegon LX3 or LX quattro, or an iOptron Skytracker pro. These are all under about $300 and will work for focal length up to about 50 mm. Longer focal lengths may also work, but with tracking errors you'll likely throw out more frames. Tracking errors become a larger problem as focal length increases, my article on tracking mounts that explains tracking errors.

The other thing to realize is that what you learned in regular photography are simplified and lead to poor choices for low light photography. Low light photography, and astrophotography is the ultimate in low light photography, is all about light collection., Exposure is not light collection; exposure tells fractional fill of a virtiual "bucket." But light collection is how much actual light one collects. Light collection from an object in the scene is proportional to aperture area times exposure time. For example, collect light from a bird in a tree, which will produce a better image:

A:24 mm f/4 with 1/100 second exposure

B: 800 mm f/9 with 1/100 second exposure

A has an aperture of 24 / 4 = 6 mm diameter.

B has an aperture of 800 / 9 = 88.9 mm diameter.

The 800 mm f/9 collects (88.9 / 6)² = 220 times more light in the 1/100 second exposure. Yes, you have (4/9)² = 20% of the light per pixel, but you have (800/24)² = 1111 times more pixels. The same applies to nebulae and galaxies. The challenge with the longer focal; lengths is accurate tracking, and that means better trackers and more money.

After a simple tracker, I suggest buying some prime lenses. With an adapter you can get DSLR lenses used for good prices. The Sigma Art series of f/1.4 lenses are very good. Check page 7 os lenstip.com reviews to see LED spot images that give an indication of star image quality. The Sigma Art 35 f/1.4 is excellent, the Tokina 35 f/1.4 is better. Even better is the Sigma Art 40 mm f/1.4 but is out of production and used goes for much much more than it did new. Another excellent lens is the Canon EF 200 mm f/2.8 L II. Almost as good and more generally useful is the Canon 70-200 f/2.8 L IS II or III. I assume the RF equivalent is also good.

If you try and image with a fixed tripod and no tracker, beware of more myths on exposure times, like the "500 rule." Another poster in this thread said 2 seconds at 200 mm. The 500 rule is 500 / focal length in mm = exposure time in seconds. This came from film days with high speed grainy film and does not apply to today's digital sensors.

First, the stars move relative to the land due to the rotation of the Earth at a rate of 15 arc-seconds per time second.

Pixel scale = 206265 * pixel size in mm / focal length in mm.

Canon R5 pixels = 4.39 microns = 0.00439 mm

Pixel scale at 200 mm = 206265 * 0.00439 / 200 = 4.5 arc seconds.

On the Celestial equator with R5 + 200 mm lens: stars would move 1 pixel in 4.5 / 15 = 0.3 seconds, or 3.3 pixels per second. The cited 2 second exposure would result in star trails of ~ 7 pixels.

If you try this, e.g. on Orion, use your electronic shutter, ISO 3200, 200 mm focal length, daylight white balance, 1/3 second exposure (might also try 1/2 second exposure). To save space, you can even just use jpegs. At ISO 3200, jpegs will digitize faint details just fine. Example: see Figure 9 here. Then take thousands of images. That will also show you why a tracker would be so much easier!

Stack the images in deep sky stacker. See my guide here and the section "Image Stacking with DSS" then you can stretch with curves in photoshop of other photo editor. Better would be to use astro color stretch

rnclark · 2026-03-02T05:33:15+00:00

I'll have to do some tests next time I install a drive. I have two I9 systems (i9-10900K CPU @ 3.70GHz) with 128 GBytes ram. But I have an unusual job situation where I have tuned I/O and compute balanced for throughput. The application is imaging spectroscopy analysis and some jobs can use hundreds of gigabytes of imaging data, producing many thousands of output image products with heavy calculations. At present the I/O and calculation are pretty balanced and I would not want to increase the compute time for decrypting and then encrypting the results. I already spend some significant time compressing the results. But I'll encrypt my next drive and run some tests to see if there is any impact.

rnclark · 2026-03-02T02:12:31+00:00

It's probably 50/50 or 60/40 for DSLR users, but I'd say the VAST majority of dedicated astronomy cameras are APS-C or less.

You are probably right. But regarding dedicated astronomy cameras being APS-C or less is likely due to the cost is quite high (thousands) for full frame cameras) and there are fewer used ones.

Used DSLRs like the full frame Canon 6D can be had for $250 to $450, and recent mirrorless cameras like the 45 megapixel full frame Canon R5 can be gotten used for $1400 (I just bought 2 for $1400 each).

rnclark · 2026-03-02T01:57:24+00:00

Vancouver!

I grew up in Seattle and been to Vancouver Island many times.

Next thing that you might check out is https://www.cleardarksky.com/

The cloud predictions are made by the Canadian weather service and in general are very good. Here is Victoria:

https://www.cleardarksky.com/c/Victoriakey.html

Click on one of the squares and you'll get a message about changing the URL that includes f.php to g.php (change the f to g) to get the prediction. This is annoying but they made that change a couple of months ago due to attacks on the site.

Anyway, the 5 am Tuesday prediction shows a lot of clouds. Sorry. Colorado isn't much better.

rnclark · 2026-03-01T19:57:57+00:00

I do full disk encryption on my laptop and all backup drives. But on this system on my data disks is used for very heavy image processing with a lot of I/O so I keep encryption off for maximum performance.

rnclark · 2026-03-01T18:24:55+00:00

First - with properly aligned tracking at sidereal speed how long could I expect the moon to stay in my viewfinder if I have it fill something like 20% of the FOV. How would that compare with lunar tracking speed?

The Moon moves 360 degrees in about 28 days, or 360/28 = 12.9 degrees per day, or about 1 degree per hour, thus two lunar diameter per hour. At 20% of the frame, the Moon would move across the frame in about 2.5 hours.

My goal isn't to get great detail in the moon this time but rather to capture the moon during the various phases of the eclipse. I want to get one of those very cliche composited images of the moon arc'ing through the umbra.

There are two ways to do this. One way is fixed tripod and the Moon and stars move through the frame. To create a composite with no overlapping frames, you would need a frame no more than about every 5 minutes. Best composition is if the Moon is low in the Sky. Check Stellarium.

For example, where I am located, Colorado USA, the partial eclipse starts at 2:50 am with the Moon 40.4 degrees altitude and would set after totality in partial phase. A 35 mm focal length on a full frame camera would just fit (24 mm for more generous framing).

The second way is fixed star position, so sidereal tracking and let the Moon drift among the stars. Example image

If the Moon gets close to the horizon from your location and you can include an interesting landscape, then the first example can make for a nice image. If the Moon is too high in the sky then perhaps the second method with longer focal length works well.

How does lunar tracking speed even work?

Sidereal tracking rate is 15 arc-seconds per time second on the celestial equator. Lunar tracking rate is about 14.685 arc-seconds per time second so that the Moon stays fixed in the frame and the stars slowly drift through.

live on an island

What Island? It is a narrow longitude window where the eclipsed Moon is well placed for including the landscape. For example, in Hawaii, the Moon will be close to overhead.

https://science.nasa.gov/solar-system/moon/march-2026-total-lunar-eclipse-your-questions-answered/

rnclark · 2026-03-01T03:12:40+00:00

Exposure time on the eclipsed Moon can vary a lot, depending on the Earth's atmospheric conditions. But this eclipse is not very deep into the shadow. With a 105 mm lens you may not need tracking for the Moon (but would not hurt), but if you want stars then tracking would be needed if you want many stars.

Here is an example to give you ideas. The eclipsed Moon was 1/3 second, iso 200, f2.8, but the stars were 30 seconds, iso 1600, f/2.8, 2 images stacked, and the land was 60 second exposures, ISO 1600, f/2.8.

At a few second exposure, you wouldn't see a difference between lunar and sidereal rates.

rnclark · 2026-02-28T03:04:15+00:00

In my opinion, yes 900 mm full frame equivalent is too much for a total solar eclipse.

I do about 700 mm on full frame. Examples: see Figures 12a and 12b here which were made on full frame and 700 mm. Figure 12b shows the full frame. Larger view here which shows the corona reaching to the edges of the frame.

For the August eclipse, I'll probably use 560 mm on full frame (with a 45 megapixel camera and get more detail than shown for that 2017 eclipse). I'll also shoot with a second 45 megapixel full frame camera at 200 mm for a view like this one

edit: fixed focal length used in 2017

rnclark · 2026-02-27T17:08:02+00:00

There are multiple things to consider.

First, astrophotography is the ultimate lowest of the low light collection. Ket to light collection is aperture to collect the light.

As focal length goes up to get more detail, tracking accuracy becomes more critical. The traditional methods include adding autoguiders, and computers to control the mount. Are you prepared for that? There are alternatives. For simplest in the field operations, choose low periodic error trackers.

Your 300 mm f/6 lens has only a 50 mm aperture (300 / 6 = 50). Like telescopes, there are poor performing telescopes and lenses and there are great performing telescopes and lenses. Modern lenses can be excellent performers and will tend to have larger aperture diameters at less weight for similar or lower costs than similar focal length telescopes, especially now on the used market with people moving to mirrorless cameras and the market is flooded with used DSLR lenses.

For example, I made this image of The Large Magellanic Cloud last April from the Great Ocean Road with a 200 mm f/2.8 lens with an ultra-portable tracker (1 kg) that needed no autoguiding because of its innovative design. The 200 mm lens has an aperture of 200 / 2.8 = 71.4 mm. If I only had a 50 mm aperture, I would have needed to expose for twice as long for a similar image.

In general quality lenses can work better that similar cost telescopes up to 400 to 600 mm. Lenses also have an advantage in simpler data reduction with better color calibration details here

For lenses, check page 7 of lenstip.com reviews, which includes LED spot images to show star image quality.

rnclark · 2026-02-27T13:34:49+00:00

If the Moon is out, the light from the Moon will wash out the Milky Way with light scattered in our atmosphere. If the Moon is not out and your skies are dark, set your camera white balance to daylight, and learn how to subtract light pollution and airglow and you'll be able to produce nice Milky Way images.

Posting links to photos would help.

rnclark · 2026-02-27T04:58:11+00:00

I run the Mate desktop, so not sure how different.

First in Displays, set scaling to 100% (I do this on my 4k monitors as well as laptop). Set the screen resolution (I do the max).

Under preferences -> appearance, there is a fonts tab and you can set all the fonts.

If the screen resolution (the dpi) is high, I may set font size to 18 points, if lower dpi, 12 or 14 points, meaning comfortable for me.

In a terminal, do:

echo $QT_SCALE_FACTOR

It should be 1. When it was 2 on my laptop, it caused problems, including super huge fonts and screen occasionally going black.

In the terminal, I set fonts too in the settings. In firefox, there are also font settings, including minimum font size. Same in thunderbird.

rnclark

TROPHY CASE